Jaya, Frederick R.Tanner, Jessie C.Whitehead, Michael R.Doughty, PaulKeogh, ScottMoritz, CraigCatullo, Renee2024-04-052024-04-05Jaya, F. R., Tanner, J. C., Whitehead, M. R., Doughty, P., Keogh, J. S., Moritz, C. C., & Catullo, R. A. (2022). Population genomics and sexual signals support reproductive character displacement in Uperoleia (Anura: Myobatrachidae) in a contact zone. Molecular Ecology, 31, 4527–4543. https://doi.org/10.1111/mec.165970962-1083http://hdl.handle.net/1885/316529When closely related species come into contact via range expansion, both may experience reduced fitness as a result of the interaction. Selection is expected to favor traits that minimize costly interspecies reproductive interactions (such as mismating) via a phenomenon called reproductive character displacement (RCD). Research on RCD frequently assumes secondary contact between species, but the geographic history of species interactions is often unknown. Population genomic data allows tests of geographic hypotheses about species origins and secondary contact through range expansion. We used population genomic data from single nucleotide polymorphisms (SNPs), mitochondrial sequence data, advertisement call data, and morphological data to investigate a species complex of toadlets (Uperoleia borealis, U. crassa, U. inundata) from northern Australia. Although the three species of frogs were morphologically indistinguishable in our analysis, we determined that U. crassa and U. inundata form a single species (synonymized here) based on an absence of genomic divergence. SNP data identified the phylogeographic origin of U. crassa as the Top End, with subsequent westward invasion into the range of U. borealis in the Kimberley. We identified six F1 hybrids, all of which had the U. borealis mitochondrial haplotype, suggesting unidirectional hybridization. Consistent with the RCD hypothesis, U. borealis and U. crassa sexual signals differ more in sympatry than in allopatry. Hybrid males have intermediate calls, which likely reduces attractiveness to females. Integrating population genomic data, mitochondrial sequencing, morphology, and behavioral approaches supplies us an unusually detailed collection of evidence for reproductive character displacement following range expansion and secondary contact.This project was funded by the Hermon Slade Foundation (to JSK), an Australian Biological Resources Survey Research Grant (to CCM), an Australian Research Council Linkage Grant (to CCM, JSK and PD), and the WA Museum's Alcoa Frog Watch programme (to PD). JCT was supported by a National Science Foundation Postdoctoral Research Fellowship in Biology under Grant No. 1811930. Open access publishing facilitated by The University of Western Australia, as part of the Wiley - The University of Western Australia agreement via the Council of Australian University Librarians.application/pdfen-AU© 2022 The Authors.https://creativecommons.org/licenses/by-nc/4.0/mitochondrial genomerange expansionreproductive interferencespeciationunidirectional hybridization2022-07-2210.1111/mec.165972022-11-13Creative Commons Attribution-NonCommercial License